In many fluidized reaction processes such as Fluidized Catalytic Cracking (FCC), Methanol to Olefins, Catalytic Dehydrogenation, and the like, there are risers in each of the catalyst regenerator vessels and the fluidized catalyst-hydrocarbon product separation vessels commonly referred to as reactors in FCC. In the case of the catalyst regenerator vessel, the riser extends vertically into the regenerator dilute phase (freeboard) to allow sufficient volume for catalyst to accumulate below the device in the annular space. In the case of the fluidized catalyst hydrocarbon product separation vessel (commonly referred to as the reactor in FCC), the riser performs the reaction and transports catalyst to the cyclonic separation device(s). Consequently because of the long length and high temperature, the riser which is supported at the bottom of the vessel at a fixed location must be guided for lateral support while accommodating expansion and contraction. The manner of guiding the riser must be flexible to account for the high axial thermal expansion of the riser relative to the vessel shell.